The present invention relates to a die cutting apparatus for cutting blanks of corrugated fiberboard, paper, metal, plastics and other materials, and particularly to a unit for separating what is called a gripper margin from a product portion and releasing the gripper margin.
A conventional die cutting apparatus comprises a blank feed unit, an endless conveyor having grippers for holding the blanks to be die-cut, a die cutting unit of a rotary or flat type, a unit for separating the scrap portion, a unit for separating the gripper margin from the product portion, and a unit for releasing the gripper margin from the gripper. By passing each blank held by gripper through these units one after another, the products cut out to a required shape can be obtained continuously.
In such a conventional apparatus, after the blank has been die-cut, the scrap portion is firstly separated from the product portion with the gripper margin. The gripper margin is then separated from the product portion, which falls and is collected. Finally, the gripper margin is released from the gripper at the upper portion of the apparatus. The scrap portions and the gripper margin thus separated are taken out of the apparatus by means of separate conveyors.
As described above, in the conventional die cutting apparatus, the release of the gripper margin from the gripper is performed some time after the separation of the gripper margin from the product portion. Therefore, the margin releasing unit has to be provided at a distance from the margin separating unit to prevent the gripper margins from becoming mixed up with the product portion. This necessitates the use of separate conveyors and thus complicates the structure of the apparatus and increases the manufacturing cost.